Effect of Yoke Pattern on Recording Characteristics of Thin Film Heads

The authors studied the dependence of the magnetic anisotropy of thin film heads on the core side angle. Because of the increase in core reluctance, it had been thought that the head efficiency decreases with increasing side angle. However, measurements revealed that the head efficiency increases with the side angle. To determine the reason for the unexpected behavior, three-dimensional calculations of the stress and stress-induced anisotropy were performed. According to these analyses, the magnitude of the tensile stress along the hard axis increases with the side angle, and therefore the anisotropy field is lower when the magnetic layer of the head has a positive magnetostriction constant. A decrease in the anisotropy field was confirmed by observations using the magneto-optical Kerr effect. It was concluded that the side angle affects the magnitude of the magnetic anisotropy, in addition to the core reluctance and the domain structure.